Device for fuel-metering, in particular, fuel-injection for internal combustion engines



Jan. 22, 1957 WOLF-DIETER BENSINGER 2,778,539

DEVICE FOR FUEL-METERING, IN PARTICULAR, FUEL-INJECTION FOR INTERNAL COMBUSTION ENGINES Orlginal Filed Sept 27 1949 United States Patent DEVICE FOR FUEL-METERING, IN PARTICULAR, FUEL-IlggECTION FOR INTERNAL COMBUSTION Wolf-Dieter Bensinger, Muhlacker, Wurttemherg, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Original application September 27, 1949, Serial No. 118,093, new Patent No. 2,673,662, datedMarch 30, 1954. Divided and this application February 24, 1954, Serial No. 412,349

1 Claim. (Cl. 222-250 The invention relates to a device forfuel-rnetering, in particular, fuel-injection for internalcombustion. en-

gines, originally disclosed in application Ser. No. 118,093,

for instance, of the fuel charge to be injected in sequence at each combustion period, that even at the highest engine speeds or highest rate of injections per minute (for v example, up to 30,000 per minute), an accurate and uniform fuel-metering is assured.

The invention, above all, is applicable to low-pressure injection, for instance, gasoline injection, if occasion arises it may, however, also be employed for high-pressure injection.

A feature of the present invention, consists essentially in that a charge of fuel of the right amount for one injection is divided off from the inflowing fuel, and hereupon this divided off and metered amount is displaced by the pressure of the subsequently inflowing fuel and then conducted to the injection point. As a rule, the fuel is delivered to the metering device under the same pressure as that of the subsequently inflowing fuel, by which it is pushed to the injection points. Fuel-displacement and metering of the subsequently inflowing fuel are here so interdependent that a practically perfect, uniform metering is attained, since only as much fuel flows into the metering device as can flow out of it.

For the practical application of the invention there is provided, in particular, a free moving, for example, reciprocating needle-like, or pin-like plunger member which is alternately seated by the fuel pressure on one or the other plunger side, whereby the plunger member performs a certain limited stroke, and thereby the fuel on the opposite side is metered and forced into the injection line.

For fuel control there is provided, for example, a reciprocating slide valve, outside of which the metering and displacing plunger may be arranged. The employment of a needle-like, or pin-like plunger member of small diameter, secures the further advantages that the mass of the plunger member may be kept very small which is of essential importance especially for a very high rate of strokes, that the fuel-metering and regula-' in the simplest manner, selectively or automatically, for example, in dependence upon the engine speed by changing the stroke of the plunger. Furthermore, driving pressure and regulating pressure are very low.

The invention is, in particular, applicable for engines with injection points becoming effective by pairs in sequence, the fuel being delivered to one pair, or several pairs of injection points by one device. However, each device may merely deliver fuel to one individual injection point, by bringing the injection line into communication alternately with one or the other side of the plunger member.

In the drawing a fuel-metering device, in which th invention is embodied, is illustrated diagrammatically by way of example, in a somewhat simplified manner,

Figs. 1 and 2 showing the plunger or control member in one or the other of the end or control positions.

In a bore a of a metering-device housing b (Fig. 1), a control valve 0 is reciprocated by a cam 61 driven," for example, at one-half crankshaft revolutions by the engine that is to be supplied with the fuel charge. In a laterally located small bore s parallel to the bore a, the'needle-like piston or plunger member a, provided with rounded ends as a plunger crown, is supported, with axial clearance e (Fig. 1) or e (Fig. 2), between the end surface f of the'bore s and the needle-like axially adjustable regulating rod g. The latter may be adjusted, manually or in some other way directly. The fuel, for instance, being conveyed by a diaphragm pump serving as delivery pump, flows at h into a control slot i, from which, depending on the axial position of the control valve 0, it flows either through the cross bore k (Fig. 1) or through the cross bore 1 (Fig. 2) into the clearance e or'the clearance e. The momentary opposite plunger end is, at this instant, either in communication with the injection line m (Fig. 1) through the cross bore 1, or in communication with the injection line n (Fig, 2) through the cross bore k.

In the axial position according to Fig. 1, the plunger member d is first in the lower position as shown. Through the fuel entering by way of it it is pushed upwardly against the regulating rod g by the pressure of the feed pump. Coincidentally it pushes the fuel, which previously has been confined at e, through 1 into the injection line m, in a metered quantity in accordance with the diameter and stroke of the plunger member. Simultaneously with this, the same amount of fuel has entered at the lower plunger side (proportionately to clearance e Fig. 2), and is there shut off from the rest of the in-flowingfuel by further axial displacement of the valve 0. As soon as the valve, after one-half rotation of the cam 01, has reached the position according to Fig. 2, the fuel through I passes over to the upper plunger side, whereby a is pushed downwardly, and the fuel, which previously has been confined at e, is then through k pushed into the injection line n. As long as the setting of the regulating rod g is not changed, the amount of fuel actually displaced and injected will always be constant. By an axial displacement of g, however, the stroke of the plunger member d and, by this way, the quantity of the inflowing and the displaced fuel may be changed and regulated. 1

Instead of only one transverse bore k and one transverse bore l arranged in the control valve, there may be provided several of them distributed on the circumference of the control valve and adapted to deliver fuel to a corresponding number of injection points. Generally, a feeding pressure of the feeding pump of approximately 4 lb. per sq. in. above the pressure in the cylinders is sufficient. Therefore, for example, for gasoline injection into the suction manifold, or into the uncompressed or low-compressed working air in the cylinder, the pump may work with relative low pressures. Nevertheless, in

ni rmitywith he invention, pressures of 1400 lbs. per qn: or more can, also be con rolled by he. dev se..-

The bores k and l are arranged so that they always 7 deliver the fuel to the same plimger side. p terile as con ol- 7 l, rely: c he ore. Q cont o s he, nflow of he fue m. h o k nd ik w se, H92 q the u fi wf i he fuel, displaced at e, from I to the injection line In e .qt e en po it on o the c nt l alve. he bore p v s ecm po e tdson ust he e d sp ed a to, m' .ne, hi eih bor rtco t o s e inflow of t e uel rom h o, l! herwise, t e m n e o per ion. s on r nc p e he'same a i e embo ieat cst n o F s- 1 an Th v ce ordto i s and f e s he ad anta e o e se en.- srtiveness against seizing, especially, in cpnneetion with a ol ne o rat on, Bu it isa o u e bl to a van a t hsrrfus aand; he pplis t pn A u on y on retenses t rm and pp ca on of t. the nyention has. been described in detail, it will be apparent. to those skilled in the, art that varions modifications, may be made without depatting from the scope h am endedfi a m- W at I c m A flui et nd. upp y ev ce comp s ng a 1 s. hay n s and second pa le b r sthere a c ntrolvalve having a uniform diameterthroughoutitslength and mounted for automatic reciprocation in the first bgre, a needle shaperl piston member with rounded ends ally mq able n h ewed ore, a pa r o butme t Four bores o,

one. end, pos t n. at the com limiting the movement of the piston member in the secsarl ba s @951. definin therewith twp sad. space one of the abutments being fixed in the housing and the other being axially movable therein, communication ducts between the end spaces and the first bore, two discharge ducts opening into the first, bore, one of said discharge ducts being at a level above its associated communication I duct, the" otherfofsaid discharge ducts being at a level below its associated"communication duct; a supply duct cation with the supply duct while the other is in communication with "one of-the discharge ducts, whereas, in the other end position of the valve, the one space. is in commiinicat'io'n with the other disch a'rge dnct while the o her 'isfiii" communication with the silpply duct.

References Cited in the file of this patent Uli'ITIfED STATES PATENTS 2,406,239 Morgenroth Aug. 20, 1946 FOREIGN PATENTS 235,587 GreatBritain Apr. 1, 1926 

